diff --git a/src/bittorrent.cpp b/src/bittorrent.cpp
index f582fbddd..f6823e5e3 100644
--- a/src/bittorrent.cpp
+++ b/src/bittorrent.cpp
@@ -45,7 +45,7 @@ bittorrent::bittorrent(){
   fs::path::default_name_check(fs::no_check);
   // Supported preview extensions
   // XXX: might be incomplete
-  supported_preview_extensions << "AVI" << "DIVX" << "MPG" << "MPEG" << "MP3" << "OGG" << "WMV" << "WMA" << "RMV" << "RMVB" << "ASF" << "MOV" << "WAV" << "MP2" << "SWF" << "AC3";
+  supported_preview_extensions << "AVI" << "DIVX" << "MPG" << "MPEG" << "MP3" << "OGG" << "WMV" << "WMA" << "RMV" << "RMVB" << "ASF" << "MOV" << "WAV" << "MP2" << "SWF" << "AC3" << "OGM" << "MP4" << "FLV" << "VOB";
   // Creating bittorrent session
   s = new session(fingerprint("qB", VERSION_MAJOR, VERSION_MINOR, VERSION_BUGFIX, 0));
   // Set severity level of libtorrent session
diff --git a/src/src.pro b/src/src.pro
index 4302cadad..09eaf37aa 100644
--- a/src/src.pro
+++ b/src/src.pro
@@ -25,8 +25,8 @@ contains(DEBUG_MODE, 0){
   message(Release build!)
 }
 
-QMAKE_CXXFLAGS_RELEASE += -fwrapv
-QMAKE_CXXFLAGS_DEBUG += -fwrapv
+QMAKE_CXXFLAGS_RELEASE += -fwrapv -O2
+QMAKE_CXXFLAGS_DEBUG += -fwrapv -O2
 
 CONFIG += link_pkgconfig
 PKGCONFIG += libtorrent libccext2 libccgnu2